Add Python protobuf support.

Python protobuf std libs will be wrapped in final binary/test par file.

Bug: b/70568913
Test: manually create real examples.
Change-Id: I7376ec9175f3e03d1adbd20858a7f74e826387ad

python/proto.go

@@ -0,0 +1,67 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package python
+
+import (
+	"android/soong/android"
+	"strings"
+
+	"github.com/google/blueprint"
+)
+
+func init() {
+	pctx.HostBinToolVariable("protocCmd", "aprotoc")
+}
+
+var (
+	proto = pctx.AndroidStaticRule("protoc",
+		blueprint.RuleParams{
+			Command: `rm -rf $out.tmp && mkdir -p $out.tmp && ` +
+				`$protocCmd --python_out=$out.tmp -I $protoBase $protoFlags $in && ` +
+				`$parCmd -o $out -P $pkgPath -C $out.tmp -D $out.tmp && rm -rf $out.tmp`,
+			CommandDeps: []string{
+				"$protocCmd",
+				"$parCmd",
+			},
+		}, "protoBase", "protoFlags", "pkgPath")
+)
+
+func genProto(ctx android.ModuleContext, p *android.ProtoProperties,
+	protoFile android.Path, protoFlags []string, pkgPath string) android.Path {
+	srcJarFile := android.PathForModuleGen(ctx, protoFile.Base()+".srcszip")
+
+	protoRoot := android.ProtoCanonicalPathFromRoot(ctx, p)
+
+	var protoBase string
+	if protoRoot {
+		protoBase = "."
+	} else {
+		protoBase = strings.TrimSuffix(protoFile.String(), protoFile.Rel())
+	}
+
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        proto,
+		Description: "protoc " + protoFile.Rel(),
+		Output:      srcJarFile,
+		Input:       protoFile,
+		Args: map[string]string{
+			"protoBase":  protoBase,
+			"protoFlags": strings.Join(protoFlags, " "),
+			"pkgPath":    pkgPath,
+		},
+	})
+
+	return srcJarFile
+}